Thin film tantalum coating for medical implants

Abstract

A method of depositing a relatively thin film of bioinert material onto a surgical implant substrate, such as a dental implant. Chemical vapor deposition (CVD) may be used to deposit a layer of tantalum and/or other biocompatible materials onto a solid substrate comprised of an implantable titanium alloy, forming a biofilm-resistant textured surface on the substrate while preserving the material properties and characteristics of the substrate, such as fatigue strength.

What is claimed is: 
     
       1. A method for depositing a tantalum coating onto an implant substrate, the method comprising the steps of:
 providing the implant substrate within a heat diffusing structure positioned within a reaction chamber, wherein the implant substrate is a metallic substrate comprising at least one of a titanium alloy, cobalt-chromium-molybdenum alloy, and stainless steel; and 
 chemical vapor depositing the tantalum coating onto the implant substrate by providing tantalum chloride gas heated to a temperature over 900° C. by a heating element, wherein the heat diffusing structure attenuates the excess radiant heat within the reaction chamber such that the implant substrate is at a temperature of 800° C. - 900° C. so as to form an angulated textured tantalum coating on the implant substrate. 
 
     
     
       2. The method of  claim 1 , wherein the tantalum coating includes a tantalum alloy. 
     
     
       3. The method of  claim 1 , wherein the heat diffusing structure is porous so as to be penetrable by the tantalum coating within the reaction chamber. 
     
     
       4. The method of  claim 3 , wherein the heat diffusing structure includes a bottom, side walls, and an open top. 
     
     
       5. The method of  claim 1 , wherein the implant substrate is a metallic substrate. 
     
     
       6. The method of  claim 1 , wherein the tantalum coating is chemical vapor deposited onto the implant substrate at a temperature between 800° C. and 850° C. 
     
     
       7. The method of  claim 1 , wherein the metallic substrate is a titanium alloy. 
     
     
       8. The method of  claim 6 , wherein the titanium alloy retains an alpha-beta microstructure that existed in the titanium alloy before the angulated textured tantalum coating was formed on the implant substrate. 
     
     
       9. The method of  claim 1 , wherein the angulated textured tantalum coating has a thickness of less than 15 microns. 
     
     
       10. The method of  claim 1 , wherein the angulated textured tantalum coating has a thickness of less than 11 microns. 
     
     
       11. The method of  claim 1 , wherein the angulated xtured tantalum coating has a thickness of approximately 4 microns. 
     
     
       12. The method of  claim 1 , wherein the angulated textured tantalum coating includes pin holes exposing the metallic substrate. 
     
     
       13. The method of  claim 1 , wherein the tantalum coating is chemical vapor deposited onto the implant substrate at a temperature below 850° C. 
     
     
       14. The method of  claim 1 , wherein the to coating is chemical vapor deposited onto the implant substrate at a temperature above 850° C. 
     
     
       15. The method of  claim 1 , wherein the tantalum coating is a single cycle chemical vapor deposition layer. 
     
     
       16. The method of  claim 1 , wherein the heat diffusing structure is a three-dimensional metallic structure including a plurality of ligaments that define open voids between the ligaments. 
     
     
       17. The method of  claim 15 , wherein the heat diffusing structure is a formed from an open-cell, porous tantalum material. 
     
     
       18. The method of  claim 1 , wherein the implant substrate is a solid substrate. 
     
     
       19. The method of  claim 1 , wherein the heating element comprises a graphite susceptor. 
     
     
       20. The method of  claim 18 , wherein the graphite susceptor is heated by an induction coil positioned in the reaction chamber.